More than 50 million people had been forced from their homes worldwide at the end of last year, the United Nations refugee agency has said.

The total number of displaced is the highest since the Second World War.

The daunting figure is also a stark reflection of the ongoing conflicts and persecutions from Syria to South Sudan. It includes refugees and asylum-seekers who fled abroad as well as people displaced within their own countries.

The UNHCR's annual Global Trends Report, published in Beirut today, says 51.2 million people had been forcibly displaced by the end of 2013 - six million more than at the end of the previous year.

The data is compiled from government, non-government partner organisations and UNHCR's own records.

Syria's civil war alone has forced nine million people to flee their homes.

Syrians fleeing the bloodletting at home and a fast-growing web of other crises across the world accounted for the spike in the displaced, the UNHCR said.

"The world has shown a limited capacity to prevent conflicts and to find a timely solution for them," said UN high commissioner Antonio Gutteres.

"Today, we not only have an absence of a global governance system, but we have sort of an unclear sense of power in the world," he told reporters in the Lebanese capital of Beirut, where the global report was launched.

The massive increase was mainly driven by Syria's civil war. By the end of last year, 2.5 million Syrians had become refugees in neighbouring countries and more than 6.5 million had been displaced within Syria, the UN agency said.

"These numbers represent a quantum leap in forced displacement around the world," Mr Gutteres added. "For the first time since the Second World War, we had in 2013 more than 50 million people displaced by conflict and persecution either crossing borders or within the borders of their countries."

Of the 51.2 million displaced worldwide last year, 16.7 million were refugees outside their countries' borders. Nearly 12 million of them are cared for by UN agencies. More than half of the refugees under UNHCR's care - 6.3 million - had been in exile for more than five years, the agency said.

By country, the biggest populations of refugees were Afghans, Syrians and Somalis, the report said. The countries hosting the largest number of refugees were Pakistan, Iran and Lebanon, whose stability is threatened by the raging Syrian war, now in its fourth year.

More than a million Syrians have registered in Lebanon as refugees since the conflict in their country started in March 2011. The refugees now make nearly a quarter of Lebanon's 4.5 million population.